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Equilibria

AQA AS-level ChemistryTopic 6 of 1620 lessons

Revision notes for Equilibria in AQA Chemistry (7404). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Dynamic EquilibriumSome reactions are reversible.
  2. Chemical EquilibriaEquilibrium can only be reached in a closed system where the reactants and products cannot escape.
  3. Le Chatelier's PrincipleThe position of equilibrium indicates the extent of a chemical reaction.
  4. Changing ConcentrationsIf the concentration of the reactants is increased the equilibrium will shift to the right.
  5. Changing PressureChanging the pressure only affects the position of an equilibrium involving gases, and only when there are different numbers of moles of gas on each…
  6. Changing TemperatureThe direction in which the equilibrium shifts depends on the sign of ΔH and whether or not the reaction is endothermic or exothermic.
  7. CatalystsA catalyst increases the rate of a reaction by providing an alternative pathway with a lower activation energy.
  8. Equilibrium Reactions in IndustrySome industrial processes involve reversible reactions.
  9. AmmoniaThe Haber process is used in the manufacture of ammonia from nitrogen gas and hydrogen gas.
  10. EthanolEthanol can be produced from glucose using yeast as a catalyst.
  11. MethanolMethanol is made from the reversible reaction between hydrogen and carbon monoxide using a copper catalyst.
  12. The Equilibrium Constant KcThe equilibrium constant Kc is a measure of the relative concentrations of products and reactants in the equilibrium system.
  13. Finding the Value of KcTo calculate the equilibrium constant, the concentrations of the reactants and products at equilibrium must be known.
  14. Example Question - 1Question: 1.00 mol of ethanoic acid and 1.00 mol of ethanol were mixed with a little acid catalyst and left to reach equilibrium at a constant…
  15. Example Question - 2Question: 1.00 mol of ethanoic acid and 1.00 mol of ethanol were mixed and left to reach equilibrium.
  16. Example Question - 3Question: 0.400 mol of SO2 and 0.200 mol of O2 were placed in a 2.00 dm3 vessel.
  17. The Effect of Changing Temperature on KcKc is only constant at a particular temperature.
  18. The Effect of Changing Concentration on the Position of EquilibriumThe equilibrium constant does not change unless the temperature changes.
  19. Kc and the Position of EquilibriumA Kc values of 1 indicates a position of equilibrium halfway between reactants and products.
  20. CatalystsA catalyst increases the rate of a reaction by providing an alternative reaction pathway with a lower activation energy.

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